The invention is broadly concerned with collection bags for vacuum cleaners, and in particular the mounting collars for such bags which seal the bags, in an airtight manner, to the air exhaust tubes of the vacuum cleaners. Such collars conventionally comprise either a single panel of thick paperboard or a pair of overlying panels. The actual sealing of the collar to the tube is effected through a frictional engagement of the collar with the tube utilizing a variety of means. Most common is the provision of a centrally apertured resiliently flexible elastomeric sheet adhesively bonded to one face of a collar panel over the central opening therethrough with the sheet flexing as the collar is introduced over the tube and maintaining itself in intimate sealing engagement with the tube. In an alternative arrangement, the panel can be provided with a sunburst effect, comprising a series of slits extending radially outward from the central collar opening to allow flexing of the panel about the opening in response to movement of the collar onto the tube for an enhanced sealing therewith. The sunburst effect and variations thereof are also particularly effective in securing the collars on tubes incorporating a positioning stop or abutment behind which the collar engages.
In those instances wherein the collar is defined by a pair of overlying adhesively bonded panels, the elastomeric sheet, can, as desired, be positioned between the panels rather than on an exterior face of one of the panels. Likewise, one of the panels can incorporate a sunburst effect or variation thereof for cooperation with the elastomeric sheet.
It is essential that the collar, other than whereat special provision is made for deformation when sealing to the tube, avoid bending or distortion which could cause a hole and air leakage, thus making the bag useless. Accordingly, the conventional collar, whether formed of one or two panels, utilizes thick paperboard with a caliper on the order of at least 31 points (0.031 inch) or greater. While paperboard of such high caliper is available, the bulk of paperboard is made in a range of 15-30 points with the broadest grades of paperboard being available within this range.
The high caliper paperboard, that is above 30 points, is made by only a few mills which must run their equipment at slower speeds to allow for more fiber build up. Further, as mills generally prefer to run their machinery at high speeds and produce calipers of greater demand, the mills that do run these high calipers consider them special production and upcharge for them.
Another problem associated with heavy caliper paperboard arise in the manner in which the paperboard is to be supplied for manufacture into the collars. For example, the conventionally used high caliper paperboard cannot readily be supplied in rolls because of the substantial tendency for the high caliper paperboard to warp near or at the roll core. Further, for any substantial shipping, storing and manufacturing economies, any rolls provided would have to be of substantial diameter. However, large diameter rolls, for example 6 foot rolls with a width of 41/2 inches for a single ply collar or 9 inches for a double ply collar (assuming a blank folded on itself to define the dual panels) would be impractical and probably dangerous in a high speed manufacturing operation.
Of particular interest with regard to the manufacture of a two panel collar is the patent to Kowalewski, 3,533,868, issued Oct. 13, 1970, wherein the collars are formed from cardboard sheets.
The environment of the invention and the state of the known prior art will also be noted in the following patents:
3,108,736: E. ANDERSON ET AL
3,297,231: J. J. FESCO
3,803,815: ANDERSON ET AL
The two patents to Anderson et al illustrate two-panel collars formed from single blanks. Fesco, while referring to three panels, utilizes only the central apertured panel as a mounting means.